This invention relates to pump structures and in particular to an accelerator pump for staged carburetors. While the invention is described with respect to its use with staged carburetors, those skilled in the art will recognize the wider applicability of the inventive principles disclosed hereinafter.
Two stage carburetors are well known in the art, and typically are exemplified by the well known four barrel carburetor finding application on a number of internal combustion engines in the United States. Four barrel carburetors have a pair of primary throttles and a pair of secondary throttles, which, by way of suitable linkages, are caused to open in a sequential manner. When both throttles are fully open, the engine is able to deliver maximum performance. In a typical carburetor of the four barrel variety, an accelerator pump is provided which delivers a small quantity of additional fuel during opening movement of the primary throttle. This additional fuel is usually necessary if the rapid and immediate response which the public is accustom is to be realized. In most four barrel carburetor arrangements, after a predetermined amount of opening of the primary throttle, the accelerator pump no longer delivers additional fuel either because it has reached the end of its travel or because a stop mechanism has been brought into action to prevent any such additional travel. The result of this situation is that the accelerator pump is not available to make an additional discharge of fuel upon opening of the secondary throttle. To overcome this deficiency, various structures have been employed to initiate additional fuel flow immediately before, at or during opening of the secondary throttle. One particularly advantageous method of accomplishing the additional fuel flow is described in the U.S. Pat. No. to Niebrzydoski, 3,764,119, issued Oct. 9, 1973, and assigned to the assignee of the present invention. Conventional carburetor structure not described hereinafter is intended to be incorporated by reference to the Niebrzydoski patent.
Although the Niebrzydoski patent works well for its intended purpose, it generally requires relatively complicated, and consequently expensive linkages to accomplish its result. The invention disclosed hereinafter overcomes this deficiency by providing a simply constructed accelerator pump which provides additional fuel as the primary throttle begins an opening movement after which the accelerator pump does not discharge additional fuel until the secondary throttle begins to open, at which time the accelerator pump will resume its movement to discharge additional fuel.
One of the objects of this invention is to provide a two position accelerating pump for a carburetor of an internal combustion engine.
Another object of this invention is to provide a low cost accelerating pump useful with two stage carburetors.
Another object of this invention is to provide an accelerating pump which provides a first discharge upon the opening of the primary throttle, after which the pump does not discharge until the secondary throttle begins to open.
Other objects of this invention will be apparent to those skilled in the art in light of the following description and accompanying drawings.